The delivery of media content through data networks has become increasingly popular in recent years. Advances in technology allow for large catalogs of media content to be viewed for selection by a user and delivered, on an ad-hoc basis, without requiring the user to wait or travel to obtain their selection.
A concern with electronic delivery of media content, however, is the enforcement of access restrictions stipulated by license agreements associated with the media content, such as time based access restrictions. To address these issues, technologies have been developed for enforcing access restrictions on playback devices having persistent or intermittent contact with a data network. For example, the time maintained by an internal clock of the playback device may be synchronized with a clock maintained by the network in order to allow the playback device to correctly measure time and to enforce access restrictions based upon such time measurements.
One problem, among others, with these approaches is their lack of applicability to disconnected electronic devices that do not possess persistent or intermittent contact with the reference time keeping device. In one aspect, disconnected devices are unable to enforce time based access restrictions under circumstances where a time based licensing restriction is measured with respect to a clock that is different than that of the disconnected devices. In a further aspect, disconnected devices are subject to timing errors due to clock drift, power outages, and user manipulation.